How do I get my contents off ipod back onto itunes following death of former computer?

Please could someone give me help with regard to this, most- nearly all my music was music transferred from my cd's and not itune purchases.. they all exist still on my ipod, but my itunes doesn't seem to have them any more or I can't find them, very frustrating, but some mr clever out there should be able to put me right... thanks, hope you can help.